Process for the preparation of ketones from esters



Patented'Sept. 12, 1933 i 1 a humanize-STATE PATENT oFFIfC -E" PRooEss roa THE PREPARATION 01s I V AKETONES FRQM -ESTERS Koloman Rka, Konstanz; Germany, assignor, by *mesne assignments, to Deutsche =Goldund e Silberf-Seheideanstaltvormals 'ltoessler, Frank- -fort-on-the Main; :Germany, a corporation iof Germany 1 V 'No Drawing Application March 13, 1930, Serial V N0. 435,657,,and in GernranyJuneZ O, 19,25

a 140mm. x (or etc-134i Itis well known that acids can be converted into tively-pure acetone with recoveryof-the. methyl ketones by heating them toelevated temperaturesfialcohol. A 1 c i f in the presence of metallic oxides. For example, Furthermore, it is possibletoconvert estersinto acetic acid'onbeing heated to an elevated temketones bya reaction in whichthe alcohol4com-' 5 perature in-the presence of calcium oxide yields ponent'ofthe ester also takes part." For example, 00

acetone. 4 e 7 if ethyl acetate is subjectedzto the reaction de- "According to this-invention, ketones are pres i d a v u i ecata v c s t' pared from esters by heating an ester, for example, oxide, oxidized iron and the like, at temperatures methyl: acetate orl ethyl acetate, and water vapor ofabout 475 C., .for' example,=notonly does the V t 10 to elevated temperatures-.ofAOO C., or more in acetic acid containedin the ester under-treatment thepresence of catalysts, such as metallicoxides' take part in the formation of the acetone, but also on compounds convertible in whole or in 1 part to the ethylalCQ OL that m re, acetonevislformed metallic oxides under the conditions ofnthe re enc r sp nds t0. the-amountof acetic acid 7 action th catalysts hi h flg etive used. The alcohol which has notbeen converted V 5 inithe inventiomma'ygbementionedthe oxides of 'i to etfl e v red. If the m tiS Gar-1 70 '25 atures. of 450Ptoe600" C the acetic-acidwhicl1is calciumflerbonate 't he 'handiron, manganese, and zinc, as well as oxides or oxy- Tied b de i same'conditiensbut a e higher 7 gen compounds off-for example, calcium,1stronmperatureyfor exampleuatabout 510 C.,'=-it-is tium, barium andimagnesium; Various mixtures possible 'to convert practically all of the ethylaceof these metallic oxygen compounds have alsoet 1 r i i been f u d t be very-effective, i V Inthe carrying out of the process of this-inven- 5; .If methyl acetate or' ethyl acetate is subjected t qn at stsa nu d t p to this reaction in-the presence-'ofcalcium oxide cially sui f a p h wasCo ai "0 or calcium carbonate, preferably precipitated on 10118 n ata sts like Oxidized fi d carrierssufih agpumice-gtone t 1 t dt which contain suchcatalystsxas calcium-oxideor present in, the ester is converted-into acetone prace h t Q ivertesters, Such *a Y I tically .quantitativelygwhile the alcohol of thees-' t o eketones; c as a ra st quan ten-methyl alcohol (or :ethyl alcohoL'asthe case 'titatively, i y rp in ime n the onehand may be, is recovered] i vthe saponificationzofjacetic ester inFthe-vapor This invention is illustratedbythe following exphase is W knownfto ep yfincom 8P5 amples: V v v pletelybecause the equilibrium pointis displaced l. Areactiontuhe isfilled with pumice stone; on toward 5ml s ide, While o b "OthBIfi a/nd which calcium carbonate-has tbeen.eprecipitated, itwas unexpected thatalcohol could beconverted and iis heated to. 550 C, Amixture'ofrequal parts i acetone yby Weight of ethyl acetate and .water are passed h r a ti n'tub :isfilled-with rusty iron andztosconvertthe purified esterintoxconpara the presentjnvention. 7).:

through the reaction tubeinxthevformgof their Chips 011 which calcium calfbonateihasmeenpre vaporsat avelocity of .100: grams per liter of re- CiDitatei-and i eatedto 510 'C. mixactionspace. 'Ihe vapors leaving thetube are con- 1 turevos'equal parts by Weight of P mt e deified ,Thyieled e O%, of theory water ispassed through thereactlon tube: int-the. Theyildofmethyl alcohol is almost quantitative. 9 f t 'j at Veloclty of P S- 9 Thisiprocess of converting'esters-into'ketones g;5535223 3 g fgi g gg fiffigg possesses specialadvantages when itzis -applied to' of E theory. fi n m 9 i d mw m e n h In' theQaboveexamp e the oxidizedironmay'be 45 cludeprlpllgneous fi ld W wbwW Qn replaced byfother 'oxides such -as zinc iorimana m e only.abo 0f l 1 ganese" oxide while the calcium carbonate may be the direct ketonizingo t S- ig Yfl l W 94091133 replaced-byioxygen compounds of such meta-ls acid Solution, Whole i tW 3 a s st'rontiurn, barium'andmagnesium; Further he ed'tq a' mp e the acetone 89 mixtures-of iron. oxidewithoxides' of zinc, man- 50 b r l? c .v p f ganese; nickel and the likehave: been found mm a v escribed invention makes'it-po i' le effective. "The presence ofsmall-amountsof iron t nv rt ud py'r sneous acid into; an ester in. the, technical oxides tof]zincfijinanganese, and such: as m'ethyl'acetate, whichtester caneasilvbe Vthe'like, as they 'are' found' ifn commerceWilli-lie separatedzfrom theiim'pui'ities which it contains, seentobe ofno disadvantage for their use in material is separated. Then itiis esterified with w I ethyl alcohol and the ethyl acetate so obtained,

preferably purified, may beworked up into acetone under conditions that will convert practicallyv all of thelester into acetone. a

By the process of this invention, it is also pos-' sible to ketonize esters in admixture with other ketonizable substances, such as ethyl alcohol, acetaldehyde, acetic acid, and so forth. The ketonizing of esters or mixtures of esters, as the case may be, which contain other ketonizable substances in'addition totlie esters, can also be carried outsuccessfully when foreign substances- 7 are present such as methyl alcoho'land the like,

which do not takepart; in the ketonizing reaction and which do not'dis'turb the reaction. This discovery makes it possible to work up mixtures which occur in commerce occasionally without the necessity of separating these mixtures beforehand into their constituents and without working them up in any preliminary way whatsoever. 1

In'the preparation jof'ace'tone from ethyl acetate the'reaction can'be carried out in such a way I that a product is obtained consistingmainly. of

acetone and which contains, inaddition, very small amounts of ester and acetaldehyde, as well as small amounts of ethyl alcohol and acetic acid. It is merely necessaryto separate the acetone from this mixture, whilethe remaining constituents can be led back into the reaction without being separatedand can be subjected to further ketonizing with fresh ethyl acetate. In view of the possibility of utilizing the byproducts again,'the ketonizing process can be carried out to advantage in such a way that less stress is placed upon the obtaining of high yields and instead large quantities of the raw materialsare passed through the tube and'thus greater pro duction is obtained without having to take into consideration losses or disturbing side reactions;

The' discovery that" the ketonizing reaction can.

becarried out in the presence of certain foreign substances which do not take part in the reaction, can be made use of in the'production of certain valuable ketone mixed products. in thepresenceof: methyl alcohol the reaction can be made to produce acetone-methylalcohol' mixtures which are known to beexcellent solvents'and which may be used directly as such without separation into their constituents.

1A further discovery has been made that the catalysts can be activated by treating'thern at elevated temperatures with oxygen or oxygencontaining gas mixtures, such as air, for example. One method of carrying outthis phase'of the invention is to interrupt the ketonizing reaction when theactivity or the ,catalysts has fallen on and to pass air or a'mixture off-airf and water. vapor-over the catalysts at temperatures of about 500 C;- When oxygen is no longer absorbed, or

when it is no .longer absorbed in appreciable amounts, the regeneration process can bestopped and theketoni'zing process-continued, In this'way 1 theoriginal high yields'a're again obtained. It is especially advantageous .to" activatethe catalysts after short intervals; thatis, atti'mes when my application For example,

a cessation or a marked diminution in the activity of the catalyst has not yet appeared. In this way high yields of 'ketones are continuously obtained. The life .of "the catalyst can also be lengthened" without interrupting the. ketonizing reaction by mixing small amounts of air together with the reaction mixture consisting, for example, of ester and water vapor which" is passed through the tube.

In the treatment of ethyl acetate according to this invention, in addition to acetone a-gas mixture is obtained which-consists of two-thirds hydrogen and one-third carbon dioxide. The hydrogen which is formed can be used by. itself or if desired, in admixture with the carbon dioxide, as an aid in the carrying out of the ketonizing reaction. It can be used, for example, for heating the reaction tube. If some air is passed through --the reaction tube together withv the' ester-water vapor mixture, a part of the hydrogen which is formed isbu'rned in thereac-tion space. Instead of using it for interior heating, the hydrogen leaving the reaction vessel may be used with or without the carbon dioxide for exterior heating of the reaction vessel; Also interior and exterior heating maybe combined.

It will be apparent that the invention broadly comprises a process of preparing ketones by heat-' ing mixtures of a vapor of an esterof an aliphatic acid with a monohydric alcohol and water vapor at temperatures between about 400 C. and

about 600 C. in the presence of oxygen com- 7 pounds of metals. N

This application is'a,continuation-impart of and water-vapor attemperaturesf between about 400-and 600'C. in the'presence of a plurality of catalytic metal oxides.

prises-heating mixtures of a vapor of an ester of an aliphatic acid with a monohydric alcohol and water-vapor at temperatures between about 400 and about 600 C. in the presence of catalytic metal oxides precipitated on a carrier.

4. Process of preparing ketones which comprises heating mixtures, of a vapor of an ester of an aliphatic acid with a monohydric alcohol and water-vaporat temperatures between about 100 and about 600. C. in the presence of oxygen compounds of iron of the group consisting of the oxidesand compounds convertible to the oxides under the] conditions'of the reaction.v

.5. Processfof preparing ketones which comprises heating mixtures of a vapor of an ester of an'aliphatic acid witha monohydric alcohol and water-vapor at temperatures between aboutv 400 and about 600 C. in the presence of oxygen and water vaporat temperatures between about Serial No. 115,683, filed June 12,

3. Process of preparing ketones which com- 400 and about 600 C. in the presence of oxygen compounds of iron and calcium of the group consisting of the oxides and compounds convertible to the oxides under the conditions ofthe reaction.

7. Process of preparing ketones which comprises heating mixtures of a vapor of an ester of an aliphatic acid with a monohydric alcohol and water-vapor at temperatures between about 400 and about 600 C.'in the presence or" oxygen compounds of iron treated with oxygen compounds of calcium of the groupconsisting of the oxides and compounds convertible to the oxide other aliphatic substances, convertible into ketones, methyl-alcohol and water in the form of their vapors at temperatures between about 400 and about 600 C., in the presence of catalytic metallic oxides. I

l0. Processof preparing actone whichcom- I prises reacting a vapor of an ester. of acetic".

acid with a monohydric alcohol and Water-vapor vapor over the catalyst.

at temperatures between about 400 and about 600 C. in the presence of' catalytic metal oxides. 11. Process of preparing ketones which comprises reacting vapors of an ester of an aliphatic acid with'a monohydric alcohol and water-vapor at temperatures between about 400 and about 600 C. in the presence of catalytic metal oxides and a small'amount of air. I

12. Process of preparing ketoneswhich comprises passing a mixtureof a vapor of an ester. 7

of an aliphatic acid with a monohydric alcohol and Water-vapor over a catalyst consisting of a catalytic metallic oxide in a reaction tube heated 600 C.-, condensing the vapors leaving the tube, separating the ketone from the mixture so obtained, and passing the remaining constituents to-temperatures between about 400 and about through the reaction tube again in admixture with further quantities of the ester.

13. Process according to'claim 12, in which the catalyst is reactivated from time to timewhen its efiiciency has diminished, by interrupting the ketonizing reaction fora short time and passing an oxygen containing gas over the catalyst.

' 14. Process according to claim 12, in which the 1'}- catalyst isreactivated from time to time when its efliciency is diminished, by interrupting the ketonizing reaction for. a short time and passing a mixture of an oxygen containing gas and water- KIOLOMAN Rome. 

